1 Introduction

This paper contains estimates for the effective reproduction number \(R_{t,m}\) over time \(t\) in various nations and other regions \(m\) of United Kingdom. This is done using the methodology as described in [1]. These have been implemented in R using EpiEstim package [2] which is what is used here. The methodology and assumptions are described in more detail here.

This paper and it’s results should be updated roughly daily and is available online.

As this paper is updated over time this section will summarise significant changes. The code producing this paper is tracked using Git. The Git commit hash for this project at the time of generating this paper was df2bbec2d38e83f3fbdb7831cf6735c960f0db5e.

2 Data

Data is obtained [3]. This contains the daily cases, hospital admissions and deaths for United Kingdom by various geographies. Here the data is accessed by specimen date, admission date and date of death.

Once history is built up an allowance for rate reported cases, admissions and deaths will be made. For now the data is cut-off a week prior to the last case date in the data. All data prior to 1 March 2020 are removed.

3 Methodology

The methodology is described in detail here.

4 Results by Nation

4.1 Cases

Below a 7-day moving average of daily case count on a log scale by nation is plotted:

Daily Cases by Nation (7-day moving average)

Daily Cases by Nation (7-day moving average)

4.2 Admissions

Below we plot cumulative hospital admissions on a log scale.

Daily Admissions by Nation (7-day moving average)

Daily Admissions by Nation (7-day moving average)

4.3 Deaths

Below a 7-day moving average of daily deaths by nation on a log scale is plotted:

Daily Deaths by Nation (7-day moving average)

Daily Deaths by Nation (7-day moving average)

4.4 Current \(R_{t,m}\) estimates by Nation

Below current (last weekly) \(R_{t,m}\) estimates are tabulated.

Estimated Effective Reproduction Number by Nation
Nation Estimate Type Daily Count (Last Week) Week Ending R - Lower CI R - Mean R - Uppper CI
England cases 1,818.7 2021-05-01 0.9 0.9 1.0
England admissions 94.6 2021-05-01 0.8 0.9 0.9
England deaths 9.4 2021-05-01 0.6 0.7 0.9
Northern Ireland cases 93.4 2021-05-01 0.9 1.0 1.1
Northern Ireland admissions 4.9 2021-05-01 0.6 0.9 1.2
Northern Ireland deaths 0.6 2021-05-01 0.2 0.7 1.5
Scotland cases 167.0 2021-05-01 0.8 0.9 0.9
Scotland admissions 8.0 2021-05-01 0.6 0.8 1.0
Scotland deaths 0.7 2021-05-01 0.3 0.7 1.4
Wales cases 45.1 2021-05-01 0.8 0.9 1.0
Wales admissions 14.1 2021-05-01 0.7 0.9 1.1
Wales deaths 0.3 2021-05-01 0.1 0.5 1.3
Estimated Effective Reproduction Number by Nation

Estimated Effective Reproduction Number by Nation

4.5 Maps of Effective Reproduction Number

Below we plot the current effective reproduction number on maps with boundaries provided by [4].

4.5.1 Cases

4.5.2 Admissions

4.5.3 Deaths

4.6 Graphs over Time

Below we plot results for each nation We filter out weeks where the upper end of confidence interval for \(R_{t,m}\) exceeds 4.

4.6.1 England

4.6.2 Northern Ireland

4.6.3 Scotland

4.6.4 Wales

5 Results by Region

5.1 Cases

Below we daily case count is plotted on a log scale by region:

Daily Cases by Region (7-day moving average)

Daily Cases by Region (7-day moving average)

5.2 Deaths

Below a 7-day moving average of daily deaths by region is plotted on a log scale:

Daily Deaths by Region (7-day moving average)

Daily Deaths by Region (7-day moving average)

5.3 Current \(R_{t,m}\) estimates by Region

Below current (last weekly) \(R_{t,m}\) estimates are tabulated.

Estimated Effective Reproduction Number by Region
Region Estimate Type Daily Count (Last Week) Week Ending R - Lower CI R - Mean R - Uppper CI
Northern Ireland cases 93.4 2021-05-01 0.9 1.0 1.1
Northern Ireland deaths 0.6 2021-05-01 0.2 0.7 1.5
Scotland cases 167.0 2021-05-01 0.8 0.9 0.9
Scotland deaths 0.7 2021-05-01 0.3 0.7 1.4
Wales cases 45.1 2021-05-01 0.8 0.9 1.0
Wales deaths 0.3 2021-05-01 0.1 0.5 1.3
North East cases 88.4 2021-05-01 0.9 1.0 1.1
North East deaths 0.3 2021-05-01 0.3 1.4 3.4
North West cases 280.1 2021-05-01 1.0 1.1 1.1
North West deaths 1.0 2021-05-01 0.2 0.5 1.0
Yorkshire and The Humber cases 348.3 2021-05-01 0.9 1.0 1.0
Yorkshire and The Humber deaths 1.0 2021-05-01 0.2 0.5 0.9
East Midlands cases 160.7 2021-05-01 0.9 0.9 1.0
East Midlands deaths 0.6 2021-05-01 0.1 0.4 0.9
West Midlands cases 171.4 2021-05-01 0.9 0.9 1.0
West Midlands deaths 1.0 2021-05-01 0.3 0.7 1.3
East of England cases 169.0 2021-05-01 0.9 0.9 1.0
East of England deaths 1.7 2021-05-01 0.6 1.1 1.8
London cases 250.1 2021-05-01 0.8 0.9 0.9
London deaths 1.4 2021-05-01 0.7 1.4 2.3
South East cases 214.9 2021-05-01 0.9 0.9 1.0
South East deaths 0.4 2021-05-01 0.2 0.6 1.4
South West cases 107.3 2021-05-01 0.8 0.9 1.0
South West deaths 1.3 2021-05-01 0.4 0.9 1.5
Estimated Effective Reproduction Number by Region

Estimated Effective Reproduction Number by Region

5.4 Maps of Effective Reproduction Number

Below we plot the current effective reproduction number on maps with boundaries provided by [5].

5.4.1 Cases

5.4.2 Deaths

5.5 Graphs over Time

Below we plot results for each nation.

5.5.1 Northern Ireland

5.5.2 Scotland

5.5.3 Wales

5.5.4 North East

5.5.5 North West

5.5.6 Yorkshire and The Humber

5.5.7 East Midlands

5.5.8 West Midlands

5.5.9 East of England

5.5.10 London

5.5.11 South East

5.5.12 South West

6 Results by NHS Region

6.1 Current \(R_{t,m}\) estimates by Region

Below current (last weekly) \(R_{t,m}\) estimates are tabulated.

Estimated Effective Reproduction Number by Region
Region Estimate Type Daily Count (Last Week) Week Ending R - Lower CI R - Mean R - Uppper CI
Northern Ireland admissions 4.9 2021-05-01 0.6 0.9 1.2
Scotland admissions 8.0 2021-05-01 0.6 0.8 1.0
Wales admissions 14.1 2021-05-01 0.7 0.9 1.1
North West admissions 13.0 2021-05-01 0.7 0.9 1.1
East of England admissions 11.7 2021-05-01 0.6 0.8 1.0
London admissions 14.7 2021-05-01 0.7 0.9 1.1
South East admissions 8.0 2021-05-01 0.5 0.7 0.8
South West admissions 5.6 2021-05-01 0.5 0.8 1.0
Midlands admissions 23.3 2021-05-01 0.8 1.0 1.1
North East and Yorkshire admissions 18.3 2021-05-01 0.7 0.9 1.0
Estimated Effective Reproduction Number by Region

Estimated Effective Reproduction Number by Region

6.2 Maps of Effective Reproduction Number

Below we plot the current effective reproduction number on maps with boundaries provided by [6].

6.3 Graphs over Time

Below we plot results for each nation We filter out weeks where the upper end of confidence interval for \(R_{t,m}\) exceeds 4.

6.3.1 London

6.3.2 South East

6.3.3 South West

6.3.4 East of England

6.3.5 Midlands

6.3.6 North East and Yorkshire

6.3.7 North West

7 Results by Upper Tier Local Authority

7.1 Highest \(R_{t,m}\) as estimated using cases

Below we plot Upper Tier Local Authorities with the highest reproduction numbers (providing they had at least 10 cases per day in last 7 days):

## Selecting by Rt_ui_95
Estimated Effective Reproduction Number by Upper Tier Local Authority
Upper Tier Local Authority Estimate Type Daily Count (Last Week) Week Ending R - Lower CI R - Mean R - Uppper CI
Moray cases 10.9 2021-05-01 1.3 1.6 2.1
Bolton cases 34.4 2021-05-01 1.3 1.5 1.8
Newcastle upon Tyne cases 18.7 2021-05-01 1.1 1.3 1.6
Derry City and Strabane cases 20.6 2021-05-01 1.1 1.3 1.6
Calderdale cases 10.7 2021-05-01 1.0 1.3 1.6
Sefton cases 10.1 2021-05-01 1.0 1.3 1.6
Blackburn with Darwen cases 11.4 2021-05-01 1.0 1.2 1.6
Kingston upon Hull, City of cases 14.4 2021-05-01 1.0 1.2 1.5
Cheshire East cases 12.1 2021-05-01 1.0 1.2 1.5
Trafford cases 16.3 2021-05-01 1.0 1.2 1.4
Lancashire cases 55.4 2021-05-01 1.0 1.2 1.3
Lincolnshire cases 29.6 2021-05-01 1.0 1.1 1.3
Barnsley cases 22.3 2021-05-01 0.9 1.1 1.3
Rochdale cases 11.3 2021-05-01 0.9 1.1 1.3
Walsall cases 10.1 2021-05-01 0.9 1.1 1.4
Oxfordshire cases 19.6 2021-05-01 0.9 1.1 1.3
Croydon cases 10.6 2021-05-01 0.9 1.1 1.4
Sheffield cases 39.1 2021-05-01 0.9 1.1 1.2
Peterborough cases 14.6 2021-05-01 0.9 1.1 1.3
Swindon cases 10.9 2021-04-30 0.8 1.1 1.3
Derbyshire cases 20.0 2021-05-01 0.9 1.1 1.2
Wigan cases 10.6 2021-05-01 0.8 1.0 1.3
Devon cases 15.6 2021-05-01 0.9 1.0 1.2
Somerset cases 11.3 2021-05-01 0.8 1.0 1.3
Slough cases 10.7 2021-05-01 0.8 1.0 1.2

7.2 Risk Quadrants

The plots below show weekly cases (or deaths) on the X-axis and the reproduction number on the Y-axis. By dividing this into 4 quadrants we can identify upper tier local authorities with high cases and high reproduction numbers, or high cases and low reproduction numbers etc.

Values where the reproduction number exceeds 3 are plotted at 3.

7.2.1 Cases

Risk Quadrants - Cases

7.2.2 Deaths

Risk Quadrants - Deaths

7.3 Map of Effective Reproduction Number (Cases)

Below we plot the current effective reproduction number estimated from case data on maps with boundaries provided by [7].

7.4 Map of Reproduction Number by Upper Tier Local Authority Over 60 days

Below the reproduction number by week for each Upper Tier Local Authority is animated over last 60 days:

8 Detailed Results

Detailed output are saved to a comma-separated value file. The file can be found here.

9 Discussion

Limitation of this method to estimate \(R_{t,m}\) are noted in [1]

  • It’s sensitive to changes in transmissibility, changes in contact patterns, depletion of the susceptible population and control measures.
  • It relies on an assumed generation interval assumptions.
  • The size of the time window can affect the volatility of results.
  • Results are time lagged with regards to true infection, more so in the case of the use of deaths.
  • It’s sensitive to changes in case (or death) detection.
  • The generation interval may change over time.

Further to the above the estimates are made under assumption that the cases and deaths are reported consistently over time. For cases this means that testing needs to be at similar levels and reported with similar lag. Should these change rapidly over an interval of a few weeks the above estimates of the effective reproduction numbers would be biased. For example a rapid expansion of testing over the last 3 weeks would results in overestimating recent effective reproduction numbers. Similarly any changes in reporting (over time and underreporting) of deaths would also bias estimates of the reproduction number estimated using deaths. It may well be that some catch-up in reported deaths is exaggerating the estimates for October.

Estimates for the reproduction number are plotted in time period in which the relevant measure is recorded. Though in reality the infections giving rise to those estimates would have occurred roughly between a week to 4 weeks earlier depending on whether it was cases or deaths. These figures have not been shifted back.

Despite these limitation we believe the ease of calculation of this method and the ability to use multiple sources makes it useful as a monitoring tool.

10 Author

This report was prepared by Louis Rossouw. Please get in contact with Louis Rossouw if you have comments or wish to receive this regularly.

Louis Rossouw
Head of Research & Analytics
Gen Re | Life/Health Canada, South Africa, Australia, NZ, UK & Ireland
Email: LRossouw@GenRe.com Mobile: +27 71 355 2550

The views in this document represents that of the author and may not represent those of Gen Re. Also note that given the significant uncertainty involved with the parameters, data and methodology care should be taken with these numbers and any use of these numbers.

11 Digital boundaries

Office for National Statistics licensed under the Open Government Licence v.3.0

Contains OS data © Crown copyright and database right 2020

References

[1] A. Cori, N. M. Ferguson, C. Fraser, and S. Cauchemez, “A new framework and software to estimate time-varying reproduction numbers during epidemics,” American Journal of Epidemiology, vol. 178, no. 9, pp. 1505–1512, Sep. 2013, doi: 10.1093/aje/kwt133. [Online]. Available: https://doi.org/10.1093/aje/kwt133

[2] A. Cori, EpiEstim: A package to estimate time varying reproduction numbers from epidemic curves. 2013 [Online]. Available: https://CRAN.R-project.org/package=EpiEstim

[3] Office for National Statistics, “Official UK Coronavirus Dashboard,” 2020. [Online]. Available: https://coronavirus.data.gov.uk. [Accessed: 07-Nov-2020]

[4] Office for National Statistics, “Countries (December 2019) Boundaries UK BUC,” 09-Oct-2017. [Online]. Available: https://geoportal.statistics.gov.uk/search?collection=Dataset. [Accessed: 07-Nov-2020]

[5] Office for National Statistics, “NUTS Level 1 (January 2018) Ultra Generalised Clipped Boundaries in the United Kingdom,” 31-Jul-2017. [Online]. Available: https://geoportal.statistics.gov.uk/datasets/nuts-level-1-january-2018-ultra-generalised-clipped-boundaries-in-the-united-kingdom. [Accessed: 07-Nov-2020]

[6] Office for National Statistics, “NHS England Regions (April 2020) Boundaries EN BUC,” 13-May-2020. [Online]. Available: https://geoportal.statistics.gov.uk/search?collection=Dataset. [Accessed: 07-Nov-2020]

[7] Office for National Statistics, “Counties and Unitary Authorities (December 2019) Boundaries UK BUC,” 11-Mar-2020. [Online]. Available: https://geoportal.statistics.gov.uk/datasets/counties-and-unitary-authorities-december-2019-boundaries-uk-buc. [Accessed: 07-Nov-2020]